Method and system for providing an uplink structure and improved channelization scheme in a wireless communication network

ABSTRACT

A method and system are provided to perform channelization in a wireless communication network, wherein the wireless communication network including at least one base station that is communicatively coupled to at least one mobile terminal. A bandwidth of the wireless communication network is divided into a plurality of zones at the base station. Resource blocks are provided at the base station to receive data symbols transmitted in the wireless communication network. A plurality of resource blocks are combined at the base station to form a physical basic channel unit which are allocated to one of the plurality of zones at the base station. A permutation is performed on the physical basic channel unit to form a logical basic channel unit. A channel is provided to communicatively couple the base station and the mobile terminal so that the mobile terminal may send an access grant message and a user identification to the base station to transmit data in the logical basic channel unit.

FIELD OF THE INVENTION

The present invention relates to the field of wireless communicationsand more particularly to a method and system for providing an uplinkstructure and a channelization scheme that allocates resource blocks orbasic channel units to corresponding zones for transmission in thewireless communication network.

BACKGROUND OF THE INVENTION

Wireless communication networks, such as cellular networks, operate bysharing resources among the mobile terminals operating in thecommunication network. As part of the sharing process, one or morecontrolling devices allocate system resources relating to channels,codes, among other resources. Certain types of wireless communicationnetworks, e.g., orthogonal frequency division multiplexed (“OFDM”)networks, are used to support cell-based high speed services such asthose under the IEEE 802.16 standards. The IEEE 802.16 standards areoften referred to as WiMAX or less commonly as WirelessMAN or the AirInterface Standard.

OFDM technology uses a channelized approach and divides a wirelesscommunication channel into many sub-channels which can be used bymultiple mobile terminals at the same time. These sub-channels can besubject to interference, which may cause data loss.

A system and method are needed for providing an uplink structure and achannelization scheme having improved voice over Internet Protocol(VoIP) capabilities and advanced interference mitigation techniques,among providing other benefits. A system and method are disclosed belowproviding an uplink structure and channelization schemes that utilizeresource blocks and frequency zones to provide improved voice overInternet Protocol (VoIP) capabilities and advanced interferencemitigation techniques.

SUMMARY OF THE INVENTION

The invention advantageously provides a method and system for providingan uplink structure and a channelization scheme that allocates resourceblocks or basic channel units to corresponding zones for transmission inthe wireless communication network.

A method is provided for performing channelization in a wirelesscommunication network, wherein the wireless communication networkincluding at least one base station that is communicatively coupled toat least one mobile terminal. A bandwidth of the wireless communicationnetwork is divided into a plurality of zones at the base station.Resource blocks are provided at the base station to receive data symbolstransmitted in the wireless communication network. A plurality ofresource blocks are combined at the base station to form a physicalbasic channel unit which are allocated to one of the plurality of zonesat the base station. A permutation is performed on the physical basicchannel unit to form a logical basic channel unit. A channel is providedto communicatively couple the base station and the mobile terminal sothat the mobile terminal may send an access grant message and a useridentification to the base station to transmit data in the logical basicchannel unit.

The invention provides another method of performing channelization in awireless communication network, the wireless communication networkincluding at least one base station that is communicatively coupled toat least one mobile terminal. A bandwidth of the wireless communicationnetwork is divided into a plurality of zones at the base station.Physical resource blocks are formed at the base station to receive datasymbols transmitted in the wireless communication network. The physicalresource blocks are allocated to one of the plurality of zones at thebase station and a permutation is performed on the physical resourceblocks to form logical resource blocks. A plurality of logical resourceblocks are combined at the base station to form a logical basic channelunit. A channel is provided to communicatively couple the base stationand the mobile terminal so that the mobile terminal may send an accessgrant message and a user identification to the base station to transmitdata in the logical basic channel unit.

The invention provides a base station for use in a wirelesscommunication system, the base station being communicatively coupled toat least one mobile terminal. The base station includes a control systemthat divides a bandwidth of the wireless communication network into aplurality of zones and forms resource blocks to receive data symbolstransmitted in the wireless communication network. The control systemcombines a plurality of resource blocks to form a physical basic channelunit and allocates the physical basic channel unit to one of theplurality of zones at the base station. The control system performs apermutation on the physical basic channel unit to form a logical basicchannel unit. The base station has an antenna that communicativelycouples the base station and the mobile terminal. The antenna receivesan access grant message and a user identification from the mobileterminal and transmits data in the logical basic channel unit, whereinthe wireless communication system is configured to transmit data havingdifferent frame sizes.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is a block diagram of an exemplary cellular communication systemconstructed in accordance with the principles of the present invention;

FIG. 2 is a block diagram of an exemplary base station constructed inaccordance with the principles of the present invention;

FIG. 3 is a block diagram of an exemplary mobile terminal constructed inaccordance with the principles of the present invention;

FIG. 4 is a block diagram of an exemplary relay station constructed inaccordance with the principles of the present invention;

FIG. 5 is a block diagram of a logical breakdown of an exemplary OFDMtransmitter architecture constructed in accordance with the principlesof the present invention;

FIG. 6 is a block diagram of a logical breakdown of an exemplary OFDMreceiver architecture constructed in accordance with the principles ofthe present invention;

FIG. 7 illustrates resource blocks having uplink pilot designs for twotransmitter systems in accordance with the principles of the presentinvention;

FIG. 8 illustrates one channelization scheme in accordance with theprinciples of the present invention;

FIG. 9 illustrates another channelization scheme in accordance with theprinciples of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As an initial matter, while certain embodiments are discussed in thecontext of wireless networks operating in accordance with the IEEE802.16m broadband wireless standard, which is hereby incorporated byreference, the invention is not limited in this regard and may beapplicable to other broadband networks including those operating inaccordance with other OFDM orthogonal frequency division (“OFDM”)-basedsystems, including the 3rd Generation Partnership Project (“3GPP”) and3GPP2 evolutions. Similarly, the present invention is not limited solelyto OFDM-based systems and can be implemented in accordance with othersystem technologies, e.g., CDMA.

Referring now to the drawing figures in which like reference designatorsrefer to like elements, there is shown in FIG. 1, an exemplarycommunication system 10 is provided in accordance with the principles ofthe present invention. Communication system 10 includes a base stationcontroller (“BSC”) 12 that controls wireless communications withinmultiple cells 14, which cells are served by corresponding base stations(“BS”) 16. In some configurations, each cell is further divided intomultiple sectors 18 or zones (not shown). In general, each base station16 facilitates communications using orthogonal frequency divisionmultiplexing (“OFDM”) with mobile and/or mobile terminals 20, which arewithin the cell 14 associated with the corresponding base station 16.The movement of the mobile terminals 20 in relation to the base stations16 results in significant fluctuation in channel conditions. Asillustrated, the base stations 16 and mobile terminals 20 may includemultiple antennas to provide spatial diversity for communications. Insome configurations, relay stations 22 may assist in communicationsbetween base stations 16 and mobile terminals 20. Mobile terminals 20can be handed off from any cell 14, sector 18, zone (not shown), basestation 16 or relay 22 to another cell 14, sector 18, zone (not shown),base station 16 or relay 22. In some configurations, base stations 16communicate with each other and with another network (such as a corenetwork or the Internet, both not shown) over a backhaul network 24. Insome configurations, a base station controller 12 is not needed.

With reference to FIG. 2, an example of a base station 16 isillustrated. The base station 16 generally includes a base controlsystem 26, e.g. a CPU, a baseband processor 28, transmit circuitry 30,receive circuitry 32, multiple antennas 34 a, 34 b and a networkinterface 36. The receive circuitry 32 receives radio frequency signalsbearing information through a receive antenna 34 a from one or moreremote transmitters provided by mobile terminals 20 (illustrated in FIG.3) and relay stations 22 (illustrated in FIG. 4). A low noise amplifierand a filter (not shown) may cooperate to amplify and remove broadbandinterference from the signal for processing. Down-conversion anddigitization circuitry (not shown) may down-convert the filtered,received signal to an intermediate or baseband frequency signal, whichis digitized into one or more digital streams.

The baseband processor 28 processes the digitized received signal toextract the information or data bits conveyed in the received signal.This processing typically comprises demodulation, decoding, and errorcorrection operations. As such, the baseband processor 28 is generallyimplemented in one or more digital signal processors (“DSPs”) and/orapplication-specific integrated circuits (“ASICs”). The receivedinformation is sent across a wireless network via the network interface36 or transmitted to another mobile terminal 20 serviced by the basestation 16, either directly or with the assistance of a relay 22.

On the transmit side, the baseband processor 28 receives digitized data,which may represent voice, data, or control information, from thenetwork interface 36 under the control of the base control system 26,and encodes the data for transmission. The encoded data is output to thetransmit circuitry 30, where it is modulated by one or more carriersignals having a desired transmit frequency or frequencies. A poweramplifier (not shown) amplifies the modulated carrier signals to a levelappropriate for transmission, and delivers the modulated carrier signalsto the transmit antennas 34 b through a matching network (not shown).Modulation and processing details are described in greater detail below.

With reference to FIG. 3, an example of a mobile terminal 20 isillustrated. Similarly to the base station 16, the mobile terminal 20includes a mobile control system 38, e.g. a CPU, a baseband processor40, transmit circuitry 42, receive circuitry 44, multiple antennas 46 a,46 b and user interface circuitry 48. The receive circuitry 44 receivesradio frequency signals bearing information through a receive antenna 46a from one or more base stations 16 and relays 22. A low noise amplifierand a filter (not shown) may cooperate to amplify and remove broadbandinterference from the signal for processing. Down-conversion anddigitization circuitry (not shown) down-convert the filtered, receivedsignal to an intermediate or baseband frequency signal, which isdigitized into one or more digital streams.

The baseband processor 40 processes the digitized received signal toextract the information or data bits conveyed in the received signal.This processing typically comprises demodulation, decoding, and errorcorrection operations. The baseband processor 40 is generallyimplemented in one or more DSPs and/or ASICs.

For transmission, the baseband processor 40 receives digitized data,which may represent voice, video, data, or control information, from themobile control system 38, which it encodes for transmission. The encodeddata is output to the transmit circuitry 42, where it is used by amodulator to modulate one or more carrier signals at a desired transmitfrequency or frequencies. A power amplifier (not shown) amplifies themodulated carrier signals to a level appropriate for transmission, anddelivers the modulated carrier signal to the transmit antennas 46 bthrough a matching network (not shown). Various modulation andprocessing techniques available to those skilled in the art are used forsignal transmission between the mobile terminal and the base station,either directly or via the relay station.

In OFDM modulation, the transmission band is divided into multiple,orthogonal carrier waves. Each carrier wave is modulated according tothe digital data to be transmitted. Because OFDM divides thetransmission band into multiple carriers, the bandwidth per carrierdecreases and the modulation time per carrier increases. Since themultiple carriers are transmitted in parallel, the transmission rate forthe digital data, or symbols, on any given carrier is lower than when asingle carrier is used.

OFDM modulation utilizes the performance of an Inverse Fast FourierTransform (“IFFT”) on the information to be transmitted. Fordemodulation, the performance of a Fast Fourier Transform (“FFT”) on thereceived signal recovers the transmitted information. In practice, theIFFT and FFT are provided by digital signal processing carrying out anInverse Discrete Fourier Transform (“IDFT”) and Discrete FourierTransform (“DFT”), respectively. Accordingly, the characterizing featureof OFDM modulation is that orthogonal carrier waves are generated formultiple bands within a transmission channel. The modulated signals aredigital signals having a relatively low transmission rate and capable ofstaying within their respective bands. The individual carrier waves arenot modulated directly by the digital signals. Instead, all carrierwaves are modulated at once by IFFT processing.

In operation, OFDM is preferably used for at least downlink transmissionfrom the base stations 16 to the mobile terminals 20. Each base station16 is equipped with “n” transmit antennas 34 b (n>=1), and each mobileterminal 20 is equipped with “m” receive antennas 46 a (m>=1). Notably,the respective antennas can be used for reception and transmission usingappropriate duplexers or switches and are so labeled only for clarity.

When relay stations 22 are used, OFDM is preferably used for downlinktransmission from the base stations 16 to the relays 22 and from relaystations 22 to the mobile terminals 20.

With reference to FIG. 4, an example of a relay station 22 isillustrated. Similarly to the base station 16, and the mobile terminal20, the relay station 22 includes a relay control system 50, e.g. a CPU,a baseband processor 52, transmit circuitry 54, receive circuitry 56,multiple antennas 58 a, 58 b and relay circuitry 60. The relay circuitry60 enables the relay 22 to assist in communications between a basestation 16 and mobile terminals 20. The receive circuitry 56 receivesradio frequency signals bearing information through a receive antenna 58a from one or more base stations 16 and mobile terminals 20. A low noiseamplifier and a filter (not shown) may cooperate to amplify and removebroadband interference from the signal for processing. Down-conversionand digitization circuitry (not shown) down-convert the filtered,received signal to an intermediate or baseband frequency signal, whichis digitized into one or more digital streams.

The baseband processor 52 processes the digitized received signal toextract the information or data bits conveyed in the received signal.This processing typically comprises demodulation, decoding, and errorcorrection operations. The baseband processor 52 is generallyimplemented in one or more DSPs and/or ASICs.

For transmission, the baseband processor 52 receives digitized data,which may represent voice, video, data, or control information, from therelay control system 50, which it encodes for transmission. The encodeddata is output to the transmit circuitry 54, where it is used by amodulator to modulate one or more carrier signals that is at a desiredtransmit frequency or frequencies. A power amplifier (not shown) willamplify the modulated carrier signals to a level appropriate fortransmission, and deliver the modulated carrier signal to the transmitantenna 58 b through a matching network (not shown). Various modulationand processing techniques available to those skilled in the art are usedfor signal transmission between the mobile terminal 20 and the basestation 16, either directly or indirectly via a relay station 22, asdescribed above.

With reference to FIG. 5, a logical OFDM transmission architecture isprovided. Initially, the base station controller 12 (See FIG. 1) sendsdata destined for transmission to various mobile terminals 20 to thebase station 16, either directly or with the assistance of the relaystation 22. The base station 16 may use channel quality indicators(“CQIs”) associated with the mobile terminals 20 to schedule the datafor transmission as well as select appropriate coding and modulation fortransmitting the scheduled data. The CQIs may be obtained directly fromthe mobile terminals 20 or may be determined at the base station 16using information provided by the mobile terminals 20. In either case,the CQI for each mobile terminal 20 is a function of the degree to whichthe channel amplitude (or response) varies across the OFDM frequencyband.

The scheduled data 62, which is a stream of bits, is scrambled in amanner that reduces the peak-to-average power ratio associated with thedata using data scrambling logic 64. A cyclic redundancy check (“CRC”)for the scrambled data is determined and appended to the scrambled datausing CRC adding logic 66. Channel coding is performed using channelencoder logic 68 to effectively add redundancy to the data to facilitaterecovery and error correction at the mobile terminal 20. Again, thechannel coding for a particular mobile terminal 20 is based on the CQI.In some implementations, the channel encoder logic 68 uses known Turboencoding techniques. The encoded data is processed by rate matchinglogic 70 to compensate for the data expansion associated with encoding.

The bit interleaver logic 72 systematically reorders the bits in theencoded data to minimize the loss of consecutive data bits. Theresultant data bits are systematically mapped into corresponding symbolsdepending on the chosen baseband modulation by mapping logic 74.Preferably, Quadrature Amplitude Modulation (“QAM”) or Quadrature PhaseShift Key (“QPSK”) modulation is used. The degree of modulation ispreferably chosen based on the CQI for the particular mobile terminal20. The symbols may be systematically reordered to further bolster theimmunity of the transmitted signal to periodic data loss caused byfrequency selective fading using symbol interleaver logic 76.

At this point, groups of bits are mapped into symbols representinglocations in an amplitude and phase constellation. When spatialdiversity is desired, blocks of symbols are processed by space-timeblock code (“STC”) encoder logic 78, which modifies the symbols in afashion making the transmitted signals more resistant to interferenceand more readily decoded at the mobile terminal 20. The STC encoderlogic 78 processes the incoming symbols and provide “n” outputscorresponding to the number of transmit antennas 34 b for the basestation 16. The base control system 26 and/or baseband processor 28, asdescribed above with respect to FIG. 2, provide a mapping control signalto control STC encoding. At this point, assume the symbols for the “n”outputs are representative of the data to be transmitted and are capableof being recovered by the mobile terminal 20.

For the present example, assume the base station 16 has two transmitantennas 32 b (n=2) and the STC encoder logic 78 provides two outputstreams of symbols. Accordingly, each of the symbol streams that areoutput by the STC encoder logic 78 is sent to a corresponding IFFTprocessor 80 a, 80 b (referred to collectively herein as IFFT 80),illustrated separately for ease of understanding. Those skilled in theart will recognize that one or more processors may be used to providesuch digital signal processing, alone or in combination with otherprocessing described herein. The IFFT processors 80 preferably operateon the respective symbols to provide an inverse Fourier

Transform. The output of the IFFT processors 80 provides symbols in thetime domain. The time domain symbols are grouped into frames, which areassociated with a prefix-by-prefix insertion logic 82 a, 82 b (referredto collectively herein as prefix insertion 82). Each of the resultantsignals is up-converted in the digital domain to an intermediatefrequency and converted to an analog signal via the correspondingdigital up-conversion (“DUC”) and digital-to-analog (“D/A”) conversioncircuitry 84 a, 84 b (referred to collectively herein as DUC+D/A 84).The resultant (analog) signals are simultaneously modulated at thedesired RF frequency, amplified, and transmitted via the RF circuitry 86a, 86 b (referred to collectively herein as RF circuitry 86) andantennas 34 b. Notably, pilot signals known by the intended mobileterminal 16 are scattered among the sub-carriers. The mobile terminal16, which is discussed in detail below, uses the pilot signals forchannel estimation.

Reference is now made to FIG. 6 to illustrate reception of thetransmitted signals by a mobile terminal 20, either directly from basestation 16 or with the assistance of relay 22. Upon arrival of thetransmitted signals at each of the antennas 46 a of the mobile terminal20, the respective signals are demodulated and amplified bycorresponding RF circuitry 88. For the sake of conciseness and clarity,only one of the two receive paths is described and illustrated indetail. Analog-to-digital (A/D) converter and down-conversion circuitry90 digitizes and down-converts the analog signal for digital processing.The resultant digitized signal may be used by automatic gain controlcircuitry (AGC) 92 to control the gain of the amplifiers in the RFcircuitry 88 based on the received signal level.

Initially, the digitized signal is provided to synchronization logic 94,which includes coarse synchronization logic 96, which buffers severalOFDM symbols and calculates an auto-correlation between the twosuccessive OFDM symbols. A resultant time index corresponding to themaximum of the correlation result determines a fine synchronizationsearch window, which is used by fine synchronization logic 98 todetermine a precise framing starting position based on the headers. Theoutput of the fine synchronization logic 98 facilitates frameacquisition by frame alignment logic 100. Proper framing alignment isimportant so that subsequent FFT processing provides an accurateconversion from the time domain to the frequency domain. The finesynchronization algorithm is based on the correlation between thereceived pilot signals carried by the headers and a local copy of theknown pilot data. Once frame alignment acquisition occurs, the prefix ofthe OFDM symbol is removed with prefix removal logic 102 and resultantsamples are sent to frequency offset correction logic 104, whichcompensates for the system frequency offset caused by the unmatchedlocal oscillators in the transmitter and the receiver. Preferably, thesynchronization logic 94 includes frequency offset and clock estimationlogic 106, which is based on the headers to help estimate such effectson the transmitted signal and provide those estimations to thecorrection logic 104 to properly process OFDM symbols.

At this point, the OFDM symbols in the time domain are ready forconversion to the frequency domain using FFT processing logic 108. Theresults are frequency domain symbols, which are sent to processing logic110. The processing logic 110 extracts the scattered pilot signals usingscattered pilot extraction logic 112, determines a channel estimatebased on the extracted pilot signals using channel estimation logic 114,and provides channel responses for all sub-carriers using channelreconstruction logic 116. In order to determine a channel response foreach of the sub-carriers, the pilot signal is essentially multiple pilotsymbols that are scattered among the data symbols throughout the OFDMsub-carriers in a known pattern in both time and frequency.

FIG. 7 illustrates resource blocks (“RB”) 70,70 a-70 n (hereinafter “RB70”) having uplink pilot designs. Two or more RBs 70 a-70 n may becombined to form a basic channel unit (BCU). The RB 70 includes pilotsymbols arranged in a pattern. The pilot symbol pattern may be employedfor channel estimation, data demodulation, and sounding, among otherpurposes.

The RB 70 may include a plurality of rows and columns. For example, theRB 70 may include twelve rows and six columns. Six symbols or tones maybe provided in each row, such as OFDM symbols among other symbol types.One of ordinary skill in the art will readily appreciate that any numberof row and columns may be used. For example, the RB 70 may be configuredof various sizes, including 12×6, 18×6, and 6×4, among other sizes. TheRB 70 may be optimized for channelization and for small packettransmission (VoIP). FIG. 7 illustrates the RB 70 having a time axisacross the columns and a frequency axis along the rows.

FIG. 7 illustrates multiple RB configurations having pilot symbolpatterns with different density configurations for a two transmittersystem. The pilot symbol density and pilot symbol pattern may beconfigured in time and frequency to accommodate different contiguousresource sizes. The pilot symbol for the first transmitter is identifiedby “1,” the pilot symbol for the second transmitter is identified by“2.” The RB 70 includes areas for pilot symbols and areas for datasignals. The pilot symbol pattern and density value may be chosen basedon the size of the contiguous resource and a multi-antenna transmissionand reception (MIMO) mode.

The frequency domain symbols are provided to an STC decoder 118, whichprovides STC decoding on both received paths to recover the transmittedsymbols. The recovered symbols are placed back in order using symbolde-interleaver logic 120, which corresponds to the symbol interleaverlogic 76 of the base station 16 transmitter.

The de-interleaved symbols are then demodulated or de-mapped to acorresponding bit stream using de-mapping logic 122. The bits are thende-interleaved using bit de-interleaver logic 124, which corresponds tothe bit interleaver logic 72 of the base station 16 transmitterarchitecture. The de-interleaved bits are then processed by ratede-matching logic 126 and presented to channel decoder logic 128 torecover the initially scrambled data and the CRC checksum. Accordingly,the CRC logic 130 removes the CRC checksum, checks the scrambled data intraditional fashion, and provides it to the de-scrambling logic 132 fordescrambling using the known base station de-scrambling code to recoverthe originally transmitted data 134.

While recovering the data 134, a CQI 136 or at least informationsufficient to create a CQI at the base station 16 is determined bychannel variation analysis logic 138 and transmitted to the base station16. As noted above, the CQI 134 may be a function of thecarrier-to-interference ratio (“CIR”) 140, as well as the degree towhich the channel response varies across the various sub-carriers in theOFDM frequency band. For this embodiment, the channel gain for eachsub-carrier in the OFDM frequency band used to transmit information iscompared relative to one another to determine the degree to which thechannel gain varies across the OFDM frequency band.

An uplink (“UL”) control structure for OFDM systems may be provided thatenables mobile terminals 20 to communicate with the base stations 16.The control structure may include an uplink acknowledge (UL ACK) channeland a dedicated control channel that feeds information back, such aschannel quality indicator (CQI) information, pre-coding matrix index(PMI) information and rank information, among other information. Themobile terminals 20 may employ the UL ACK channel for initial access tothe OFDM system, for bandwidth requests, to trigger continuation ofnegotiated service, and for proposed allocation of a re-configurationheader, among other purposes. Furthermore, a downlink acknowledge (DLACK) channel may be provided to acknowledge UL data transmission. The DLACK channel may include n tones that are spread over the entire band.The DL ACK channel may be power controlled for an intended user, whereinpower control may be provided by assigning a channel to each user.

A fixed number of resources may be allocated to control channels,including UL ACK channels, DL ACK channels, UL power control channelsand multi-case control channels. The fixed number of resources may besignaled from a super-frame control. A set of ACK channels may bedefined for all unicast assignments and a separate set of ACK channelsmay be defined for group assignments. The ACK channels that are used fora given packet transmission are determined by the partition number andthe layer. The ACK signals are transmitted over several ACK tiles, wherean ACK tile is defined as a group of contiguous tones or sub-carriers.The value of the ACK signals may be determined by either non-coherentdetection or coherent detection. An orthogonal spreading code may beused to multiplex multiple ACK signals onto the same ACK tile.

An uplink control channel structure supports UL ACK channels for bothunicast assignments and group assignments. The UL control channelstructure also supports multiple ACKs for different packets that aretransmitted on the same resources, as in multi-codeword MIMO(“MCW-MIMO”) or multi-user MIMO (“MU-MIMO”). The UL control channel alsoprovides feedback for frequency selective scheduling and pre-coding,including for simple diversity assignments.

For MU-MIMO, separate unicast messages are provided for each user thatis assigned to a same partition. A unicast control segment may include aMU-MIMO header or a multicast message that is targeted to the lowergeometry user in an assignment. The header may include a message typethat indicates a number of layers that are multiplexed on the sameresources. Furthermore, the header may include a PMI used for thetransmission in the case of codebook based pre-coding feedback. The PMIis a matrix having a number of columns equal to a number of layers,wherein each column includes a pre-coding vector for the correspondinglayer.

A fixed number of resources may be allocated for the UL dedicatedcontrol channel. The resources are divided into UL control tiles,wherein the number of tiles allocated to a user depends on the amount offeedback requested. The allocated tiles may be spread over the band toobtain frequency diversity. The UL control information is CRC protectedand is scrambled by the user ID. The content of the information canchange each feedback instance to accommodate event driven controlinformation such as a bandwidth request.

A UL random access (“RA”) channel may be provided to enable the user toinitially gain access to the system through one of several physicalcontrol structures. According to one embodiment, the UL random accesschannel is a designated resource. The UL random access channel may be acontention based channel for multiple mobile terminals 20 to requestaccess/bandwidth. A designated resource may be allocated for theseaccess requests. The access request may be spread or repeated across theresources that are used exclusively for random access and bandwidthrequests. The mobile station 20 may randomly select from one sequenceand location if multiple possibilities are available.

According to one embodiment, the mobile terminal 20 may randomly selectfrom one of L sequences, which spans N RBs 70. Alternatively, thesequence length L may be chosen to confine a full sequence within an RB70. By confining the spreading sequence to one RB 70, the spreadingsequences maintain orthogonality as the RB 70 is virtually frequencyflat as the RB contains physical contiguous tones. The spreadingsequences may be repeated in each RB 70 to gain diversity.

If many resources are assigned for uplink control, the resources may bedivided into M time-frequency blocks for random access. In this case,the number of distinct codes/resource per sub frame is LM, where thevalue of M may be dynamically specified by the base station 16. In someembodiments, a sub-frame within a superframe (or otherwise specified asset of F frames) is also randomly selected, wherein the number ofdistinct codes/resource/sub frames per superframe is defined as LMF.

Another physical control structure includes overlaying the random accessrequests with UL control signals. The access request may be spread orrepeated across the resources used for uplink control, such as CQI,among other uplink control. The mobile terminal 20 may randomly selectfrom one sequence and location if multiple possibilities are available.For example, the mobile terminal 20 may randomly select from one of Lsequences, where L is less than or equal to the RB size. By confiningthe spreading sequence to one RB 70, the spreading sequences maintainorthogonality as the RB 70 is virtually frequency flat as the RB 70includes physical contiguous tones or sub-carriers. The length-Lsequence is completely repeated on each of the N RBs 70. Coherentcombining of each sequence repetition may improve detection at the basestation 16.

While overlaying the RA request and UL signals, the resources may bedivided into M time-frequency blocks for random access if many resourcesare assigned for uplink control. A number of distinct codes or resourcesper sub-frame is LM. The values of N and M may be dynamically specifiedby the base station 16. In some embodiments, a sub-frame within thesuperframe (or otherwise specified as a set of F frames) is alsorandomly selected. In some embodiments, the sequences span the N RBs 70.The sequence length in these cases is LN and the number of distinctcodes or resource per sub frame is LNM.

In some embodiments, the L sequences are an orthogonal set of spreadingsequences, wherein the L-sequences may be divided into two types ofindications. A first type includes a system access request without apreviously assigned mobile terminal ID and a second type includes asystem access request with an assigned mobile terminal ID. If a mobileterminal 20 is granted access to the system, a down link (DL) controlsegment access grant may be scrambled by the sequence/resource block ID.An access grant message may include a user identification of the mobileterminal 20 that initiated a request for access. The access grantmessage may be provided in the UL control segment. The access grantmessage may be scrambled by a sequence that the mobile terminal 20 usedin the UL random access channel. The UL control segment may include anMCCS having a combination index and/or permutation index and a RAB ifpersistent resources have been allocated, including unicast assignmentmessages for individual assignments and group assignment messages forgroup assignments. Persistent resources may be allocated using apersistent assignment message, which are different for UL and DLassignments. Each message may include a resource identification for thebasic channel unit (BCU) and a number of resources assigned.Alternatively, a bitmap may be provided that indicates the assignedresources. For the bitmap, the length of the bitmap may be the length ofthe persistent zone. The length may be signaled in the super-framecontrol. The UL persistent assignment message may be included in the ULcontrol segment. Alternatively, the UL persistent assignment message maybe included in a separate partition. The UL/DL persistent assignmentmessages may be scrambled by a user identification of an intended user.The base station 16 may attempt interference cancellation to remove theRA channel from UL control.

Another physical control structure includes overlaying the RA channelover the wideband UL resources. The request is spread or repeated acrossthe UL channel, possibly across the entire bandwidth. The random accessoperation for users may be assigned to one length L sequence and onelocation, if multiple possibilities are available.

A random access channel may be assigned one length L sequence for use byall users. The total resources NT may be divided into M time-frequencyblocks for random access. The access sequence, through spreading andrepetition, may span NT/M=N RB's (e.g. N=3). The mobile terminal 20 mayrandomly select one of the M, wherein the number of distinction resourceper sub frame is M. The sub frame for a request is also randomlyselected.

The sequences for random access may be an orthogonal set of spreadingsequences. Two sequences may be defined for two types of indications. Afirst type includes a system access request without a previouslyassigned mobile terminal ID and a second type includes a system accessrequest with an assigned mobile terminal ID. If a mobile terminal 20 isgranted access to the system, a down link (DL) control segment accessgrant may be scrambled by the sequence/resource block ID. The basestation 16 may attempt interference cancellation to remove the RAchannel from UL control. The base station 16 may attempt to decode ULcontrol and traffic transmissions with and without an assumption that anRA was sent.

The invention provides an improved channelization and control channeldesign for sub-frames, such as WiMAX sub-frames. The WiMAX basic framestructure includes super-frames, frames, sub-frames and symbols. Eachsuper-frame may span 20 ms and may be divided into four equally-sized 5ms radio frames. According to one embodiment, each 5 ms radio frame mayinclude eight sub-frames. A sub-frame may be assigned for either DL orUL transmission. Three types of sub-frames may be employed: a sub-framehaving six OFDM symbols; a sub-frame having five OFDM symbols and asub-frame having seven OFDM symbols.

Channelization for control and traffic may be provided within eachsub-frame and may span across the symbols within the correspondingsub-frame. The invention uses a separate zone to support extendedsub-frames for both UL and DL. The extended sub-frames may be defined toconcatenate sub-channel resources across multiple sub-frames, to reducecontrol overhead resources and improve UL coverage.

The bandwidth may be divided into a plurality of zones, including adiversity zone, a localized zoned and an extended frame zone. The zonesinclude a one-dimensional ordered list of resources, in units of a basicchannel unit (“BCU”). In other words, the partitioning of resourcesbetween the diversity zone, the localized zones and the extended framezone is performed using BCUs. The diversity zone may be used to supportdiversity assignments. The localized zone may be used to supportlocalized assignments, or frequency selective scheduling, to optimize aconnection quality based on relative signal strengths of specific users.The zones also may apply fractional frequency reuse (“FFR”) to controlco-channel interference and support universal frequency reuse, withminimal degradation in spectral efficiency. With FFR, mobile terminals20 located near the base station 16 may operate on zones having allsub-channels available. Alternatively, with FFR, mobile terminals 20located near the edge of the cell (i.e., far from the base station 16)may operate on zones having less than all sub-channels available.

According to one embodiment, the BCU may include three resource blocks.The resource blocks may include 12 sub-carriers and 6 OFDM symbols.Defining a BCU size to include three RBs provides several advantages.Three RBs provide sufficient granularity and flexibility for VoIPassignments, whereas for non-VoIP assignments, the resource unit doesnot have granularity constraints. In other words, a BCU having three RBsprovides a trade-off between channel estimation performance and pilotoverhead resources. For group assignments, such as VoIP, the groups areallocated in units of BCUs. By contrast, individual VoIP users mayreceive resources in units of RBs. Furthermore, three RBs correspond to394 kHz, which provide acceptable frequency selective schedulingperformance.

FIG. 8 illustrates one channelization procedure wherein band 802 isdivided into a plurality of resource blocks 804 a-804 n havingcontiguous tones, which are identified by sub-carriers A, B, C and D.Three contiguous RBs are grouped together to form physical BCUs 806a-806 n. The physical BCUs 806 a-806 n are allocated to one of aDiversity Zone 1 (808), a Diversity Zone 2 (810), a Diversity Zone 3(812) and a Localized Zone (814). The physical BCUs 806 a-806 n in zones808, 810, 812 and 814 are evenly spread throughout the band 802. Thephysical BCUs 806 a-806 n within each zone are permuted at 820, 822 and824 using a sector specific BCU permutation to form logical BCUs.

FIG. 9 illustrates another channelization procedure wherein band 902 isdivided into a plurality of resource blocks (“RBs”) 904 a-904 n havingcontiguous tones, which are identified by sub-carriers A, B, C and D.Each physical resource block 904 a-904 n is allocated to one of aDiversity Zone 1 (908), a Diversity Zone 2 (910), a Diversity Zone 3(912) and a Localized Zone (914). The physical RBs 904 a-904 n in zones908, 910, 912 and 914 are evenly spread throughout the band 902. Thephysical RBs 904 a-904 n within each zone are permuted at 920, 922 and924 using a sector specific BCU permutation to form logical RBs. ThreeRBs are grouped together to form logical BCUs.

Basic channel units (“BCU”) in the extended frame zone may use the samechannelization as in the non-extended frame zone. According to oneembodiment, the control channel for the extended frame zone may occurevery k-frames and the assignments in the extended frame zone may bedefined for k-frames. The control channel may support multi-cast andunicast control. The unicast control information may be contained withinan associated partition in a first sub-frame. According to oneembodiment, transmission using extended sub-frames may co-exist withtransmissions using non-extended sub-frames. Thus, only mobile terminals20 that use the extended zone are affected by the increased latency.

Once a mobile terminal 20 accesses the system, the mobile terminal 20may request resources on the UL to transmit information to the basestation 16. The mobile terminal 20 may be provided with several optionsfor performing the UL resource request. Parameters for a firsttransmission may be specified by a bandwidth request, the parameters maybe set to default based on capability negotiation, the parameters may beset to a previous configuration based on renewal, or the parameters maybe set in some other manner. The mobile terminal 20 may change theassignment parameters by including an additional re-configurationmessage encoded with data that takes effect at the start of the nextpacket transmission. This takes advantage of HARQ for the controlmessage.

The mobile terminal 20 may randomly select an RA signaling ID. Asignaling ID may be a specific spreading sequence, a time-frequencylocation, a time slot, an interlace, or other signaling ID. The set ofsignaling ID options are known to users and also the index associatedwith each signaling ID option.

In response to a random access channel signal, the base station 16 mayassign one or more of a user ID to the user, an initial UL resource forthe mobile to provide information, user equipment capabilities, a DLresource assignment requesting information from the mobile terminal andadditional details, such as group assignment, base station procedures,among other parameters. The assignment message may carry user IDinformation.

A message sent to the mobile terminal 20 from the base station 16 mayidentify the base station 16 using a randomly selected signaling IDoption that is selected by the user for the RA. For example, if thecontrol channels are generally scrambled in some manner by the user IDin response to a RA, the base station 16 will send a control messagescrambled by the index of the randomly selected signaling ID, such assequence index, sequence location, etc.

In another embodiment, some signaling IDs may be reserved for users thathave been assigned user IDs. For example, a user may be in a hand-offoperation and may be accessing a new serving sector. A user may selectfrom a set of random access signaling IDs if an assigned user ID is notprovided. Alternatively, a user may select from a different subset ofsignaling options if the user does have a user ID. In response, the basestation 16 may send a control message that is scrambled by the RA signalindex and includes a user ID if the mobile terminal 20 has sent asignaling option indicating a user ID is not provided. Alternatively, ifthe mobile terminal 20 has sent a signaling option indicating it doeshave a user ID, then the base station 16 may send a control message thatis scrambled by the RA signal index without a user ID. The mobileterminal 20 may indicate the user ID in the next UL transmission foruser equipment capabilities, etc.

According to one embodiment, the header and optionally a message bodymay be added to a first packet transmission. Alternatively, the headerand optionally a message body may be added to a first packettransmission and every Nth packet afterwards, where N can be from 1 toinfinity. The base station 16 may provide the mobile terminal 20 with anACK/NAK of packet transmission to indicate that a re-configurationmessage was correctly received.

During an assignment of the mobile terminal 20, users may embed a headeron a data packet transmission that provides details on configuration orre-configuration. The request by the mobile terminal 20 for UL resourcesmay be made on dedicated resources within UL control tiles. Theseresource sizes may be different for different frames according to apre-determined pattern. The sizes may be known at the mobile terminal 20and the base station 16, so signaling is not needed after configuration.

According to one embodiment, the resource request may occupy a fieldthat is reserved for another message (CQI, ACK/NAK, precoder index,etc.). The presence of a request may be specified by the UL controlmessage type. The mobile terminal 20 may set this type to a messageconfiguration that includes space for a resource assignment. As aresult, the size of the message may not be changed from the specifiedsize for that sub frame. The presence of the request field may bedynamic, but may not affect the pre-determined size of the user's ULcontrol. A resource request may be encoded with other UL control data sothat resource requests may be reliably received.

The request may have multiple forms for a given system. In a firstembodiment, the resource request may be a single “on/off” indication.Details of an assignment may be given in a re-configuration message ormay be known from previous or default configurations. Alternatively, theresource request may be a message, where details of assignments areindicated, such as delay constraints, QoS, packet backlog, and resourcesize, among other assignments. Details of an assignment may be given ina re-configuration message or may be known from previous or defaultconfigurations. For example, resources may be specified by a secondarybroadcast channel, UL resources may be allocated across distributed RBblocks, bandwidth requests may be 4-10 bits indicating QoS and a firsttransmission spectral efficiency or a mobile terminal 20 buffer size, abandwidth request may occupy a field otherwise assigned for anotherpurpose, such as DL CQI feedback, or UL resources may be encoded withother UL control data for users so that a bandwidth request may bereliably received.

According to an alternative embodiment, users may be assigned one of therandom access signaling IDs (e.g., channel sequences or location) afteraccessing a system. A resource request may use the same sequence orchannel configurations. As with the RA channel, users also may beassigned specific sub frames for resource request opportunities. Theassigned signaling may be a unique identifier for a user's resourcerequest. In a first example, a set of signaling IDs may be reserved forresource requests and may not be used for RA requests. The assignedsequence or location may be a unique identifier for a user's resourcerequest. A user may be assigned signaling IDs to identify a bandwidthrequest or a resource request. Alternatively, users may be assignedsignaling IDs from a full set of RA signaling IDs. The sequence may bescrambled by resource request ID to identify as BW or resource request.The assigned sequence, location, or scrambling may be a uniqueidentifier for a user's resource request. Users may be assigned multiplesignaled IDs for different configured services, such as VoIP and httptraffic resource requests, among other configured services. If the userhas another mechanism for obtaining resource requests, and opportunitiesfor resource requests are frequent, the user may not be assignedsignaling for transmitting resource requests in this manner.

According to yet another embodiment, a UL bandwidth or resource requestmay use resources that are specified persistently. One or more RBs andmultiple RBs may be distributed to provide diversity. A UL bandwidth orresource may be overlaid with other traffic on a same resource as atraffic signal or a control signal. If the user has another mechanismfor resource requests and opportunities for requests are frequent, theuser may not be assigned signaling for transmitting resource requests inthis manner. UL bandwidth and resource requests for the mobile terminal20 may include 4-10 bits, with an initial message containing limitedfields, such as QoS and a first transmission spectral efficiency or amobile terminal buffer size including CRC. The UL bandwidth requests andresource requests for a mobile terminal 20 are intended to be reliablesignaling with diversity, with interference cancellation used at thebase station 16. Users may be separated by locations of RBs, sub frame,and assigned sequences. Regarding sequences, each user may be assigned asequence block to use. In other embodiments, users may be assigned asame set of sequences to facilitate detection at the base station 16.Alternatively, orthogonal sequences such as Zadoff-Chu or Walshsequences may be used. The sequence length may be less than the lengthof the RB. If N RBs are assigned for each resource request channel, itmay be repeated over all RBs. Alternatively, the sequence may be spreadover all N RBs.

The mobile terminal 20 may send a request for a service signal. Themessage size may be minimal as it indicates a renewal or continuation ofa configured service. According to a first option, the service may berenewed through a single message after the mobile terminal receives a ULassignment for a given type of service. The message may be a simpleON/OFF toggle to renewal service with previous or existing parameters.The message may be sent in a persistently assigned UL control resourcespace and the message type may indicate that the service renewal isbeing signaled. The mobile terminals 20 may be assigned multiplemessages to toggle multiple services, parameters of renewal for firsttransmission may be set to a default and a re-configuration signal infirst transmission may provide parameter changes.

Alternatively, a scrambled ED may be provided to the mobile terminal 20for a UL renewal request. After the mobile terminal 20 receives a ULassignment for a given type of service, the service may be renewedthrough a single message. The message may be a simple ON/OFF toggle torenew service with previous or existing parameters. The message may besent using resource requests in random access space to renew service tolast configuration parameters. The mobile terminals 20 may be assignedmultiple messages to toggle multiple services. The parameters of renewalfor a first transmission may be set to a default.

The invention may be realized in hardware, software, or a combination ofhardware and software. Any kind of computing system, or other apparatusadapted for carrying out the methods described herein, is suited toperform the functions described herein.

A typical combination of hardware and software could be a computersystem having one or more processing elements and a computer programstored on a storage medium that, when loaded and executed, controls thecomputer system such that it carries out the methods described herein.The invention can also be embedded in a computer program product, whichcomprises all the features enabling the implementation of the methodsdescribed herein, and which, when loaded in a computing system is ableto carry out these methods. Storage medium refers to any volatile ornon-volatile storage device.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed herein above. In addition, unless mention was made above tothe contrary, it should be noted that all of the accompanying drawingsare not to scale. A variety of modifications and variations are possiblein light of the above teachings without departing from the scope andspirit of the invention, which is limited only by the following claims.

1. A method of performing channelization in-a wireless communicationnetwork, the wireless communication network including at least one basestation that is communicatively coupled to at least one mobile terminal,the method comprising: dividing a bandwidth of the wirelesscommunication network into a plurality of zones at the base station;forming resource blocks at the base station to receive data symbolstransmitted in the wireless communication network; combining a pluralityof resource blocks at the base station to form a physical basic channelunit; allocating the physical basic channel unit to one of the pluralityof zones at the base station; performing a permutation on the physicalbasic channel unit to form a logical basic channel unit; providing achannel to communicatively couple the base station and the mobileterminal; and initiating the mobile terminal to send an access grantmessage and a user identification to the base station to transmit datain the logical basic channel unit.
 2. The method according to claim 1,wherein the bandwidth is divided into at least one of a diversity zoneand a localized zone.
 3. The method according to claim 1, wherein threeresource blocks are combined to form the physical basic channel unit. 4.The method according to claim 1, wherein the permutation performed onthe physical basic channel unit is a sector specific permutation.
 5. Themethod according to claim 1, wherein the zones include fractionalfrequency reuse to adjust resources available to the mobile terminalbased on a distance between the base station and the mobile terminal. 6.The method according to claim 5, wherein the fractional frequency reusegrants all resources to the mobile terminal located close to the basestation and grants limited resources to the mobile terminal located farfrom the base station.
 7. The method according to claim 1, wherein thedata symbols include tones.
 8. A method of performing channelization ina wireless communication network, the wireless communication networkincluding at least one base station that is communicatively coupled toat least one mobile terminal, the method comprising: dividing abandwidth of the wireless communication network into a plurality ofzones at the base station; forming physical resource blocks at the basestation to receive data symbols transmitted in the wirelesscommunication network; allocating the physical resource blocks to one ofthe plurality of zones at the base station; performing a permutation onthe physical resource blocks to form logical resource blocks; combininga plurality of logical resource blocks at the base station to form alogical basic channel unit; providing a channel to communicativelycouple the base station and the mobile terminal; and initiating themobile terminal to send an access grant message and a useridentification to the base station to transmit data in the logical basicchannel unit.
 9. The method according to claim 8, wherein the bandwidthis divided into at least one of a diversity zone and a localized zone.10. The method according to claim 8, wherein three logical resourceblocks are combined to form the logical basic channel unit.
 11. Themethod according to claim 8, wherein the permutation performed on thephysical resource blocks is a sector specific permutation.
 12. Themethod according to claim 8, wherein the zones include fractionalfrequency reuse to adjust resources available to the mobile terminalbased on a distance between the base station and the mobile terminal.13. The method according to claim 12, wherein the fractional frequencyreuse grants all resources to the mobile terminal located close to thebase station and grants limited resources to the mobile terminal locatedfar from the base station.
 14. The method according to claim 8, whereinthe data symbols include tones.
 15. A base station for use in a wirelesscommunication system, the base station being communicatively coupled toat least one mobile terminal, the base station comprising: a controlsystem configured to: divide a bandwidth of the wireless communicationnetwork into a plurality of zones; form resource blocks to receive datasymbols transmitted in the wireless communication network; combine aplurality of resource blocks to form a physical basic channel unit;allocate the physical basic channel unit to one of the plurality ofzones at the base station; and perform a permutation on the physicalbasic channel unit to form a logical basic channel unit; and an antennathat communicatively couples the base station and the mobile terminal,the antenna receiving an access grant message and a user identificationfrom the mobile terminal and transmitting data in the logical basicchannel unit, wherein the wireless communication system is configured totransmit data having different frame sizes.
 16. The base stationaccording to claim 15, wherein the control system divides the bandwidthinto at least one of a diversity zone, a localized zone and the extendedframe zone.
 17. The base station according to claim 15, wherein thecontrol system combines three resource blocks to form the physical basicchannel unit.
 18. The base station according to claim 15, wherein thecontrol system performs a sector specific permutation on the physicalbasic channel unit.
 19. The base station according to claim 15, whereinthe control system performs fractional frequency reuse on the pluralityof zones to adjust resources available to the mobile terminal based on adistance between the base station and the mobile terminal.
 20. The basestation according to claim 19, wherein the control systems usesfractional frequency reuse to grant full resources to the mobileterminal located close to the base station and grant limited resourcesto the mobile terminal located far from the base station.